Re: Attribute propagation to semantic actions (Spirit Qi 2.5.2)

Anatol Zolotusky <[email protected]> writes:

> I'm trying to call a semantic action upon parsing of a sequence of 3
> strings, for which I defined void do_triple() function.  (There are 2 other functions defined - for reasons explained below).  I thought that the attribute type for the parser:
>     tripleExp = attrname >> predicate >> attrvalue
> where each of the sequence members has attribute of std::string,
> according to the attribute propagation rules, would have the type of 
>     boost::fusion::tuple<std::string, std::string, std::string>
>
> But NOOOO - the code as posted gives a compilation error:
> /usr/include/boost/spirit/home/support/action_dispatch.hpp:204:19: error: could not convert ‘attr’ from ‘std::basic_string<char>’ to ‘boost::fusion::tuple<std::basic_string<char>, std::basic_string<char>, std::basic_string<char> >’
>              f(attr);
>                    ^
> And of course, when I define the semantic action as do_string, it does
> compile, and prints the last string in the expression.  Which is of
> course not what I want - I need all three (the do_vector doesn't
> compile too).
>
> What am I doing wrong, and how to fix this? (I read the post of 02/12
> "Attribute Propagation and Attribute Compatibility" by Hartmut, but
> still can't help my problem).  Using Boost 1.55, Spirit 2.5.2

I haven't really tried your code, but are you perhaps just missing a
pair of parenthesis?

-             tripleExp = attrname >> predicate >> attrvalue [&do_triple];
+             tripleExp = (attrname >> predicate >> attrvalue) [&do_triple];

> ==============================
> #include <boost/spirit/include/qi.hpp>
> #include <boost/fusion/include/tuple.hpp>
>
> #include <iostream>
> #include <fstream>
> #include <string>
> #include <map>
> #include <vector>
> namespace client
> {
>     namespace qi = boost::spirit::qi;
>     namespace ascii = boost::spirit::ascii;
>     
>     typedef boost::fusion::tuple<std::string, std::string, std::string> v3;
>
>     typedef std::vector<std::string> vs;
>     using namespace boost::fusion;
>     void do_triple(v3 tup)
>     {
>         std::cout << "got this tuple: " << std::endl;
>         std::cout << get<0>(tup) << std::endl;
>         std::cout << get<1>(tup) << std::endl;
>         std::cout << get<2>(tup) << std::endl;
>     }
>
>     void do_vector(vs tup)
>     {
>         BOOST_FOREACH(std::string s, tup)
>         {
>             std::cout << s << std::endl;
>         }
>     }
>
>     void do_string(std::string tup)
>     {
>         std::cout << "tup is apparently a string - why??? " << tup << std::endl;
>     }
>
>     template <typename Iterator>
>     struct search_query_grammar : qi::grammar<Iterator, 
>                                               ascii::space_type>
>     {
>         search_query_grammar() : search_query_grammar::base_type(start)
>         {
>             using qi::lit;
>             using qi::string;
>             start =  lit("-query") >> '=' >> tripleExp;
>             tripleExp = attrname >> predicate >> attrvalue [&do_triple];
>             attrname =  +(ascii::alnum);
>             attrvalue = +(ascii::alnum);
>             predicate = string(">") | string("<") | string("==");
>         }
>         qi::rule<Iterator, ascii::space_type> start;
>         qi::rule<Iterator, v3(), ascii::space_type> tripleExp;
>         qi::rule<Iterator, std::string()> attrname,  attrvalue,  predicate;
>         
>     };
> }
>
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-- 
CYa,
  ⡍⠁⠗⠊⠕

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